Sound-absorbing wedge

ABSTRACT

A wedge-shaped sound-absorbing structure is positioned and hung similar to a conventional ceiling system. The wedge functions as a sound-absorbing structure to limit noise exposure in industrial areas. The wedge is formed of boards which have a sound-absorbing characteristic.

1 1 Dec. 31, 1974 United States Patent 1191 Adams et al.

GD 30 3 3 H3 00 mm 1 2,730,942 1/1956Peterson........................... 2,753,440 2,840,179 2,886,859

[ SOUND-ABSORBING WEDGE 7/1956 Warefield..... 6/1958 Junger Inventors:George R. Adams, Lancaster;

William T. Meisenbacli, Columbia, both of Pa.

5/1967 Alexieff... l/1973 ECk6l,.............

v. n a P m 0 C .k m. a P g mm m C mm AL a e n g m S A 3 7 1,279,1450/1961 France.............,............. 181/33 GD 0/1956France................

[22] Filed: Apr. 12, 1974 0/1958 France....

[21] Appl. No.: 460,387

Related US. Application Data Continuation-impart of Ser. No. 302,651972, Pat. No. 3,819,010.

Primary Examiner-Richard B. Wilkinson Assistant Examiner-Vit W. Miska 3,Nov.

posig 1 struc- [57] ABSTRACT A wedge-shaped sound-absorbing structure istioned and hung similar to a conventional ceilin [52] US. 1181/33 GD,181/33 GE, 52/144 [51] Int. E04g 1/99, GlOk 11/04 [58] Field of Search1.81/33 G, 33 GE, 33 GD;

52/144 145 tem. The wedge functions as a sound-absorbing ture to limitnoise exposure in industrial areas. The wedge is formed of boards whichhave a soundabsorbing characteristic.

[56] References Cited UNITED STATES PATENTS 5/1939 Bedeil 181/33 GD 7Claims, 4 Drawing Figures 1 SOUND-ABSORBING WEDGE CROSS-REFERENCE TORELATED APPLICATION This application is a continuation-in-part ofapplican'ts copending application Ser. No. 302,,653, filed Nov. 1, 1972,entitled Sound-Absorbing Wedge, now US. Pat. No. 3,819,010.

BACKGROUND OF THE INVENTION Maximum Allowable dBA Level Hours ofExposure A certain percentage of the workers will still experiencework-associated hearing losses at these exposure ranges, but they havebeen established as a realistic initial goal. It is believed that by1980, the maximum 8- hour exposure level may be lowered from the present90 dBA to somewhere between 85 and 88 dBA.

The decibel, when used as a unit of sound measurement, is a logarithmicfunction of the sound intensity. A reduction of 3 decibels correspondsto a halving of the sound intensity.

The dBA scale of measurement responds to noises much as does the humanear; that is, it emphasizes the importance of the middle frequenciesrequired for good communication and reduces the significance of thelower frequencies. The Occupational Safety and Health Act requirementsare referenced to the A Scale of measurement. The following are someexamples of various common noises:

Noise Source Decibels Jet aircraft at take-off 1401 50 Threshold of pain140 Loud power mower 107 Food blender 9095 Stenographic work in a largeoffice 80 Range of conversation 60 70 Quiet residence at night 40Whisper Threshold of hearing (youth) 0 The first three above methods arepreferred since the wearing of ear plugs could possibly cause operatordiscomfort and would require enforcement by the employer. Theapplication herein is directed to the third control technique.

Acoustical ceilings are old in the art and the art has also used bafflesand screens on ceilings for additional sound-absorbent purposes. U.s.Pat. No. 2,884,512 shows something similar to a wedge structure which isused as part of an overall ceiling system. However, the structure in theabove-mentioned patent is built into the overall ceiling system and istied in with the lighting system and the fire protection system of aroom.

Similar types of sound-absorbing baffle structures are shown in US Pat.Nos. 2,753,440, 2,886,859. 2,160,638, 2,730,942 and in French Patents68,820 and 1,1 1 1,836. In each case, these structures appear to be anacoustical material which is surrounded by a metal covering.

French Patent 1,279,145 should also be noted because it does disclose awedge-shaped acoustical structure. Here, metal-covered acousticalmaterial is formed into resonating panels bent at an angle of alongtheir mid-lines. These panels are then assembled together to form anacoustical wedge.

SUMMARY OF THE INVENTION The invention herein is directed to awedge-shaped sound absorber made from acoustical panels or boards. Aframe structure segment is made to form a triangular wedge-shapedstructure. This frame segment provides two triangular cross members andat least one interconnecting member to form a metal frame which iswedgeshaped. Acoustical board side panels are placed in the frame. Thesound absorber is designed so that it can be suspended from any existingceiling and made a continuous structure across a room or spaced 1 ormore apart so as to minimize interference with existing sprinkler andlighting installations. The angled shape provides an attractive soundabsorber and its irregular shape helps dissipate sounds. Acousticalmaterial may be inserted into the inside of the wedge structure or anacoustical backer panel may be placed across the top of the wedge. Whenthe wedge is provided with a closed back, the inside of the wedge actsas a soundabsorbing chamber. The wedge can be readily installed inposition and any number of them can be installed in close proximity tonoisy machinery.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a perspective view of oneform of the invention herein;

FIG. II is a perspective view of a connecting member of the skeletonframe for the wedge;

FIG. III is a perspective view of one form of cross member for theskeleton frame of the continuous form; and

FIG. IV is an end view of a modified cross member structure for thecontinuous form invention described herein.

DESCRIPTION OF THE PREFERRED EMBODIMENT With reference to the drawingsherein, the soundabsorbing wedge 2 is designed to be mounted below thestructural ceiling 4 of any room.

The sound-absorbing wedge 2 is formed from a framework of approximately1 inch metal corner molding, which is nothing more than thin pieces ofmetal bent in the middle with a 90 angle between the sides. These piecesof corner molding are notched and folded together to form two triangularmembers 3. Interconnecting member 7 is used to connect together thelower corner of each of the two triangular end members. The structure ismounted in position with a corner of the end members facing downwardly.There is thus provided a skeleton metal framework 6 which will serve tohold two acoustical rectangular boards 8 in position. The acousticalboards are conventional perforated surface acoustical boards such as iswell-known in the art in most conventional ceiling systems. The boardsare simply fiberboard structures which are provided with perforations inthe surface thereof to assist the board to act as a sound absorber. Theboards are not provided with a metal facing nor are they providedsandwiched between two metal surface structures. The acoustical boards 8are placed in the framework 6 along the two sides of the skeletonframework. The foremost visible ceiling acoustical board 8, as shown inFIG. I, is held on two opposite sides by the metal triangular framework3 and on one other side by the connecting member 7. Triangularacoustical boards 9 are placed in the end of the acoustical wedge withinthe triangular metal framework 3. This forms a wedge-shaped structurewhich has the point of the wedge facing downwardly away from the ceilingstructure 4. It can thus be seen that the wedge is made from a metalframework which consists of two triangular end members and aninterconnecting metal member 7 which forms an open skeleton wedge-shapedframe. Member 10 is a hanger strap shaped like a U, with the width ofthe U being onefourth inch less than the length of the wedge and withthe legs of the U being 3" or more in length if desired. The legs of theU pass through a slot in the upper flange of the triangular members 3.Into this frame are placed two triangular acoustical boards and tworectangular acoustical boards to form the resulting acoustical soundwedge.

There is a cavity within the wedge. As is shown in the exposed portionof FIG. I, within this cavity, there are placed bags 31 ofsound-absorbing material. The bags of sound-absorbing material would bethin l-mil thick plastic bags which are filled with a mineral wool,fiberglass or inorganic aggregate. In particular, the bags have beenprepared from I-mil polyethylene plastic material and have been filledwith 500 grams of mineral wool each. A number of these bags could thenbe placed in the open cavity in the backside of the soundabsorbing wedge2. These bags greatly increase the sound-absorbing ability of thesound-absorbing wedge 2. It is obvious that backer batts, boards orother means may be used in lieu of bags to provide additional acousticalmaterial.

It is also true that an acoustical board could be placed on top of thewedge to close in the third side of the wedge and form a sound-absorbingchamber totally enclosed within the wedge structure.

The invention shown in FIG. I has been used specifically in a printingpress room. In an area of 1,250 square feet of ceiling surface over thepress structures, there were placed a total of 174 wedge-shaped soundabsorbers which constitute about 1,000 square feet of acoustical board.These were suspended three inches from a conventional acoustical boardceiling system and were spaced apart about one foot. As shown in FIG. I,any conventional hanging structure or the previously described U-shapedhanger strap 10 could be used to hold the wedge 2 in place relative toceiling. Through the use of the above wedges on the ceiling, it waspossible to secure a reduction of three dBA in the sound level of theroom. This was sufficient in all areas of the press room to meet therequirements of the Occupational Safety and Health Act as proposed for1980.While the number of decibels may appear to be a small change, itmust be remembered that three decibels correspond to a halving of thesound intensity. Higher reductions (57 dBA) are experienced whenacoustical absorbers are added to a live room (one having had noprevious acoustical treatment as is usually the case). Relieving of thesound intensity secured a very favorable reaction from the workersinvolved with the presses.

Referring now to FIG. II, there is shown a perspective end view of theconnecting member 7 which connects the two opposite corners of thetriangular end members 3. The included angle between the surfaces 11 and12 of the connecting member is approximately 60. It can be readily seenthat one of the rectangular acoustical boards 8 will rest on surface 11while the opposite surface 12 will have the second rectangularacoustical board resting thereon.

As shown in FIG. I. the triangular end member is formed from a rightangle corner molding which is nothing more than a thin piece of metalbent in the middle with a angle between the sides. One of these anglemoldings is notched at two points and bent together to form anequilateral triangle.

In many installations, large relatively open spaces must be treated andlabor costs for inserting small. individual wedges are high. Therefore,there was developed the concept of continuous wedges running the fullspan of the room. the advantage of this continuous system is the use ofbasic acoustical ceiling suspension systems to form continuous wedgesspaced at some distance apart. this allows the contractor to install alarge amount of absorbent material without incurring problems associatedwith the addition of a continuous acoustical ceiling to an existingspace. Other advantages are:

1. Easy access for maintenance of piping, etc. above the units.

2. Elimination or minimization of the need to relocate existing lightfixtures.

3. Eliminate the problems of relocating an existing sprinkler system.

FIGS. III and IV show another embodiment with the modification of thestructure of the triangular end member 3 of FIG. I for use in thecontinuous wedge described hereafter. Here a conventional inverted Trunner is used instead of a right angle corner molding. This thenprovides a triangular end member with a web 13 that will have flanges l4and 15 on opposite sides thereof. If such a structure were used in theembodiment of FIG. I, the shown acoustical ceiling boards 8 would restupon flange I5. Flange 14 would be exposed if it were the end of acontinuous wedge or else it would function as the triangular crossmember for an adjacent wedge. In effect, the structure of the FIG. "Iembodiment provides for the mounting of two wedges in an abuttingend-to-end relationship. Such a structure would be composed of a numberof triangular cross or end members. These cross members are supportedfrom acoustical ceiling type main runners 16 and 17 at the two 45 anglesof the cross member (see FIG. IV). The cross members are inter-connectedwith one another at the lower or 90 angle by a member such asillustrated in FIG. II. This structure is then capable of supportingacoustical boards in a side-by-side relationship, and the structure ofFIG. III would actually support the ends of four boards. The two boardsforming the right-hand wedge would rest upon the flanges 14 while thetwo boards forming the left-hand acoustical wedge would rest upon theflanges 15. Naturally, there would be used only a triangular acousticalboard at the two ends of the combined two or more adjacent sound wedgesand no triangular acoustical board would be used with the intermediatecross members.

In another embodiment shown in FIG. IV, an alternative technique isshown for mounting the support framework in position within aconventional ceiling system. A conventional ceiling system is providedwith two adjacent inverted T-shaped main runner structures 16 and 17.Normally, a flat ceiling board would be placed between these two mainrunner structures and would rest upon the flanges of the main runnerstructures. In lieu of this board structure, a sound-absorbing wedge isplaced therein. Triangular end cross-members would be utilized, exceptthe third side of the triangular end members would be removed and only aV-shaped end member would be utilized, and it would have the same crosssection structure as the end members of FIG. I. That is, normally thetriangular end members would be made from right angle metal. However,they could possibly be made from the structure of FIG. III. For the sakeof simplicity, a structure similar to that of FIG. III is shown whereintwo inverted T-shaped runner members are formed into a V. The runnermembers 18 and 19 have flanges 20 and 21 on which the ceiling boards mayrest. They also have vertical ribs 22 and 23 which are connected byrivets or other means to a flat metal structure 24 which is thehypotenuse of the triangular end member and this also serves as thecrossbar between said parallel runners l6 and 17. the flat metalstructure 24 has tabs 25 and 26 which extend through the vertical ribs27 and 28 of the main runners l6 and 17. The tabs may be left extendedor preferably they are bent over, and this helps to lock the flat metalpiece 24 in position to the two adjacent main runner structures 16 and17. The V-shaped structure is therefore supported by the flat metalstructure 24 from the main runners l6 and 17. Ceiling boards may then beplaced upon the flanges 20 and 21 to form a wedgeshaped acousticalstructure. Appropriate triangular end panels may be placed within thetriangular end member structure at each end of the module. Acousticalfiller or more preferably, a 2 X 4' lay-in backer panel is inserted inthe top of each modular segment of the continuous wedge.

What is claimed is:

1. In a room which is subjected to a high decibel noise level and wherethere is a closed room structure with a ceiling therein, the improvementcomprising the placing of sound-absorbing wedges suspended from theceiling, said sound-absorbing wedges constituting a support means intowhich is placed a plurality of soundabsorbing boards to form awedge-shaped structure which is triangular in cross section, saidsupport means being composed of triangular-shaped end members and aninterconnecting member connecting together one corner of each of thetriangular end members, said corners of the triangular end members whichare connected together by the interconnecting member being positionedfacing downwardly toward the area below the ceiling, saidsound-absorbing boards being triangular boards which fit within thetriangular end members to form the ends of the wedge structure andrectangular sound-absorbing board structures which fit within thesupport means resting upon the interconnecting mem ber and the sides ofthe end members, said support means and boards forming a wedge-shapedsoundabsorbing structure which increases the soundabsorbing ability ofthe overlying ceiling system and a plurality of wedge structures areplaced in an abutting relationship to form a continuous wedge structurewhich may extend from'one side to an opposite side of the room.

2. The sound-absorbing wedge ofclaim I wherein the backside of the wedgeadjacent to the ceiling is open and into which is placed asound-absorbing material.

3. The sound-absorbing wedge of claim 2 wherein said sound-absorbingmaterial is in bags formed of l-mil plastic material and containing veryloose lowdensity material, preferably of an inorganic nature.

4. The sound wedge of claim 1 wherein the open backside of the wedge iscovered over by a third rectangular sound-absorbing board to convert theinterior of the wedge into a sound chamber.

5. The sound wedge of claim 1 wherein the continuous wedge structure iscomposed of two triangular end members and at least one intermediatetriangular member interposed between said two triangular end members.

6. The sound wedge of claim 5 wherein the intermediate triangular crossmember is formed with sides that have a cross-section which is in theshape of an inverted T so that there is a web structure and flanges oneither side of said web structure whereby the flanges on one side of theweb structure support the rectangular sound-absorbing boards of onewedge structure and the flanges on the other side of the web structuresupport the sound-absorbing boards of an adjacent abutting wedgestructure.

7. The sound wedge of claim 1 wherein the triangular end member iscomposed of two sides which support the two rectangular sound-absorbingboards and a third side which is connected directly to the inverted T-shaped runner members of a typical ceiling suspension system to fastenthe sound-absorbing wedge structure to an existing suspended ceilingsystem and to place it as an integral part of an existing ceiling systemsince the sound-absorbing wedge is being used as a replacement for aceiling board which would normally be positioned between the twoadjacent inverted T-shaped runner members of the existing ceilingsystem.

1. In a room which is subjected to a high decibel noise level and wherethere is a closed room structure with a ceiling therein, the improvementcomprising the placing of soundabsorbing wedges suspended from theceiling, said sound-absorbing wedges constituting a support means intowhich is placed a plurality of sound-absorbing boards to form awedge-shaped structure which is triangular in cross section, saidsupport means being composed of triangular-shaped end members and aninterconnecting member connecting together one corner of each of thetriangular end members, said corners of the triangular end members whichare connected together by the interconnecting member being positionedfacing downwardly toward the area below the ceiling, saidsound-absorbing boards being triangular boards which fit within thetriangular end members to form the ends of the wedge structure andrectangular sound-absorbing board structures which fit within thesupport means resting upon the interconnecting member and the sides ofthe end members, said support means and boards forming a wedge-shapedsound-absorbing structure which increases the sound-absorbing ability ofthe overlying ceiling system and a plurality of wedge structures areplaced in an abutting relationship to form a continuous wedge structurewhich may extend from one side to an opposite side of the room.
 2. Thesound-absorbing wedge of claim 1 wherein the backside of the wedgeadjacent to the ceiling is open and into which is placed asound-absorbing material.
 3. The sound-absorbing wedge of claim 2wherein said sound-absorbing material is in bags formed of 1-mil plasticmaterial and containing very loose low-density material, preferably ofan inorganic nature.
 4. The sound wedge of claim 1 wherein the openbackside of the wedge is covered over by a third rectangularsound-absorbing board to convert the interior of the wedge into a soundchamber.
 5. The sound wedge of claim 1 wherein the continuous wedgestructure is composed of two triangular end members and at least oneintermediate triangular member interposed between said two triangularend members.
 6. The sound wedge of claim 5 wherein the intermediatetriangular cross member is formed with sides that have a cross-sectionwhich is in the shape of an inverted T so that there is a web structureand flanges on either side of said web structure whereby the flanges onone side of the web structure support the rectangular sound-absorbingboards of one wedge structure and the flanges on the other side of theweb structure support the sound-absorbing boards of an adjacent abuttingwedge structure.
 7. The sound wedge of claim 1 wherein the triangularend member is composed of two sides which support the two rectangularsound-absorbing boards and a third side which is connected directly tothe inverted T-shaped runner members of a typical ceiling suspensionsystem to fasten the sound-absorbing wedge Structure to an existingsuspended ceiling system and to place it as an integral part of anexisting ceiling system since the sound-absorbing wedge is being used asa replacement for a ceiling board which would normally be positionedbetween the two adjacent inverted T-shaped runner members of theexisting ceiling system.